My ZZ4 came with a Holley 770CFM carb. Want to know what carbs other ZZ4 guys are running. According to the formulas it should be a 650. I have problems with it choking, at WOT from a stand still, for second them going.

You are correct in thinking that the standard formula for carb size says you should have a 650.  But that assumes 100% volumetric efficiency and all other ideal conditions.  In Dyno tests, ZZ4 engines seem to perform best with 700 or bigger carbs.  Every ZZ4 I have known about has responded very welll off the line, so you apparently have a tuning problem.  If you bought the complete engine from GM, go back to them first.  They are quite often anxious to please.  Otherwise find a good performance tuner in your area. 

Good luck
Larry

I've had a 650 edlebrock(carter basically) on my zz4 at the beginning... it was "ok"... did lack a little 'oomph' so to speak... did get better gas milage(around 22-24ish).. now there is a holley 750 doublepump that was acquired when i bought the car back in 2000... it works well(probably could stand to be rebuilt), and still gets about 20ish mpg...

Thanks guys, I'll leave the carb as is. I'm putting in new plugs and will tune it and see if that helps. I think it was running rich since the one plug I removed was black, so I'll change them all out.